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Structural design and mechanical responses of closely spaced super-span double tunnels in strongly weathered

Jiaxin HE; Shaohui HE; Xiabing LIU; Jinlei ZHENG

《结构与土木工程前沿(英文)》 2022年 第16卷 第6期   页码 685-703 doi: 10.1007/s11709-022-0824-2

摘要: This paper presents a study of closely spaced double tunnels in Taizhou, China. One is Xiabei Mountain No. 2 four-line super-span high-speed railway tunnel (HRT), and the other is Xiabei Mountain double-line large-span subway tunnel (ST). The excavation spans of HRT and ST are 26.3 and 14 m, respectively. The two tunnels are located at different levels, and their separating distance is 17.2 m. Due to the short construction period, the HRT excavation was completed earlier than ST. The structural design of the HRT, taking account of the disturbance by the ST construction, was analyzed by a numerical simulation. It was found that the “yielding principle” design was more feasible than the “resistance principle” design when considering the safety and durability of the HRT secondary lining. The mechanical responses of the HRT during ST construction were comprehensively monitored and analyzed, including the vault settlement, horizontal convergence, surrounding rock pressure, and the internal stress in shotcrete and steel arch. Results show that the longitudinal influence range of the ST construction on the HRT was approximately 0.6–1.1 times the ST outer diameter; the disturbance was mainly generated in the ST upper bench excavation; and the final axial force of the HRT shotcrete was approximately 9–16 times that of the steel arch, which indicated that the shotcrete was the main bearing structure. The safety status of the HRT was assessed based on the monitoring data, and the minimum safety factors of the HRT shotcrete and steel arch were 1.61 and 1.89, respectively. Parametric studies were performed to show how the lining stress of HRT was affected by the relative angle, pillar width, ST excavation method and excavation footage. Finally, the design and construction optimization were proposed according to the monitoring data and parameter analysis results. This study might provide practical reference for similar projects.

关键词: double tunnels     super-span     structural design     mechanical response     numerical simulation     field monitoring    

Weakening behavior of waterproof performance in joints of shield tunnels under adjacent constructions

《结构与土木工程前沿(英文)》   页码 884-900 doi: 10.1007/s11709-022-0912-3

摘要: Groundwater leakage in shield tunnels poses a threat to the safety and durability of tunnel structures. Disturbance of adjacent constructions during the operation of shield tunnels frequently occurs in China, leading to deformation of tunnel lining and leakage in joints. Understanding the impact of adjacent constructions on the waterproofing performance of the lining is critical for the protection of shield tunnels. In this study, the weakening behavior of waterproof performance was investigated in the joints of shield tunnels under transverse deformation induced by adjacent construction. First, the relationship between the joint opening and transverse deformation under three typical adjacent constructions (upper loading, upper excavation, and side excavation) was investigated via elaborate numerical simulations. Subsequently, the evolution of the waterproof performance of a common gasket with a joint opening was examined by establishing a coupled Eulerian–Lagrangian model of joint seepage, and a formula describing the relationship between waterproof performance and joint opening was proposed. Finally, the weakening law of waterproofing performance was investigated based on the results of the aforementioned studies. It was determined that the joints with the greatest decline in waterproof performance were located at the tunnel shoulder in the upper loading case, tunnel crown in the upper excavation case, and tunnel shoulder in the side excavation case. When the waterproof performance of these joints decreased to 50% and 30%, the transverse deformations were 60 and 90 mm under upper loading, 90 and 140 mm under upper excavation, and 45 and 70 mm under side excavation, respectively. The results provide a straightforward reference for setting a controlled deformation standard considering the waterproof performance.

关键词: shield tunnel     waterproof performance     horizontal transverse deformation     joint opening     weakening behavior    

铁路隧道建设理念和设计原则

王梦恕,张梅

《中国工程科学》 2009年 第11卷 第12期   页码 4-8

摘要:

铁路隧道的建设正处于前所未有的大发展时期,笔者在总结大量工程成功经验和失败教训的基础上提出了铁路隧道建设的基本理念:隧道必须建成遗产工程;隧道必须进行科学的风险评估;隧道建设必须合理工期、合理造价、合理合同、合理施工方案和设计原则;隧道必须进行信息化施工。提出了单双线隧道选择、隧道纵坡及辅助导洞设置、支护结构设计以及快速施工等隧道设计原则。隧道建设的理念和设计原则可指导今后铁路隧道的规划、设计和施工。

关键词: 铁路隧道     建设理念     设计原则    

Damage on lining concrete in highway tunnels under combined sulfate and chloride attack

Rongrong YIN, Chenchen ZHANG, Qing WU, Baocheng LI, He XIE

《结构与土木工程前沿(英文)》 2018年 第12卷 第3期   页码 331-340 doi: 10.1007/s11709-017-0421-y

摘要:

The combined effect from sulfate and chloride is one of the important reasons to cause the damage of lining concrete in highway tunnels. To investigate the effect of chloride ions on the corrosion of lining concretes under sulfate attack, ultrasonic detecting, compression test and X-ray Diffraction (XRD) were performed on the concretes to obtain the ultrasonic velocity, corrosion thickness, compression strength and corrosion products. The ultrasonic results, compression strength and XRD patterns confirmed that the existence of chloride certainly depressed the corrosion damage on the lining concretes under sulfate attack, and the depressing effect increased with the content of chloride in the composite solution. The corrosion damage on the concretes experienced three stages independent of the composition of corrosive solution: initial slower enhancement on the strength, stabilization period and linear degradation period. The existence of chloride mainly affected the final degradation stage and obviously decreased the corrosion thickness.

关键词: lining concrete     sulfate     chloride     compression     ultrasonic    

Efficient Identification of water conveyance tunnels siltation based on ensemble deep learning

Xinbin WU; Junjie LI; Linlin WANG

《结构与土木工程前沿(英文)》 2022年 第16卷 第5期   页码 564-575 doi: 10.1007/s11709-022-0829-x

摘要: The inspection of water conveyance tunnels plays an important role in water diversion projects. Siltation is an essential factor threatening the safety of water conveyance tunnels. Accurate and efficient identification of such siltation can reduce risks and enhance safety and reliability of these projects. The remotely operated vehicle (ROV) can detect such siltation. However, it needs to improve its intelligent recognition of image data it obtains. This paper introduces the idea of ensemble deep learning. Based on the VGG16 network, a compact convolutional neural network (CNN) is designed as a primary learner, called Silt-net, which is used to identify the siltation images. At the same time, the fully-connected network is applied as the meta-learner, and stacking ensemble learning is combined with the outputs of the primary classifiers to obtain satisfactory classification results. Finally, several evaluation metrics are used to measure the performance of the proposed method. The experimental results on the siltation dataset show that the classification accuracy of the proposed method reaches 97.2%, which is far better than the accuracy of other classifiers. Furthermore, the proposed method can weigh the accuracy and model complexity on a platform with limited computing resources.

关键词: water conveyance tunnels     siltation images     remotely operated vehicles     deep learning     ensemble learning     computer vision    

Influence of advanced engineering measures on displacement and stress field of surrounding rock in tunnels

《结构与土木工程前沿(英文)》 doi: 10.1007/s11709-023-0966-x

摘要: Based on significant improvements in engineering materials, three advanced engineering measures have been proposed—super anchor cables, high-strength concrete anti-fault caverns, and grouting modification using high-strength concrete-to resist fault dislocation in the surrounding rock near tunnels crossing active strike-slip faults. Moreover, single- or multiple-joint advanced engineering measures form the local rock mass-anti-fault (LRAF) method. A numerical method was used to investigate the influence of LRAF methods on the stress and displacement fields of the surrounding rock, and the anti-fault effect was evaluated. Finally, the mechanism of action of the anchor cable was verified using a three-dimensional numerical model. The numerical results indicated that the anchor cable and grouting modification reduced the displacement gradient of the local surrounding rock near the tunnels crossing fault. Furthermore, anchor cable and grouting modifications changed the stress field of the rock mass in the modified area. The tensile stress field of the rock mass in the modified anchor cable area was converted into a compressive stress field. The stress field in the modified grouting area changed from shear stress in the fault slip direction to tensile stress in the axial tunnel direction. The anti-fault cavern resisted the dislocation displacement and reduced the maximum dislocation magnitude, displacement gradient, and shear stress. Among the three advanced engineering measures, the anchor cable was the core of the three advanced engineering measures. An anchor cable, combined with other LRAF measures, can form an artificial safety island at the cross-fault position of the rock mass to protect the tunnel. The research results provide a new supporting idea for the surrounding rock of tunnels crossing active strike-slip faults.

关键词: anti-fault effect     engineering measures     LRAF method     stress and displacement field     tunnel-crossing active faults    

Centrifuge experiments for shallow tunnels at active reverse fault intersection

Mehdi SABAGH, Abbas GHALANDARZADEH

《结构与土木工程前沿(英文)》 2020年 第14卷 第3期   页码 731-745 doi: 10.1007/s11709-020-0614-7

摘要: Tunnels extend in large stretches with continuous lengths of up to hundreds of kilometers which are vulnerable to faulting in earthquake-prone areas. Assessing the interaction of soil and tunnel at an intersection with an active fault during an earthquake can be a beneficial guideline for tunnel design engineers. Here, a series of 4 centrifuge tests are planned and tested on continuous tunnels. Dip-slip surface faulting in reverse mechanism of 60-degree is modeled by a fault simulator box in a quasi-static manner. Failure mechanism, progression and locations of damages to the tunnels are assessed through a gradual increase in Permanent Ground Displacement (PGD). The ground surface deformations and strains, fault surface trace, fault scarp and the sinkhole caused by fault movement are observed here. These ground surface deformations are major threats to stability, safety and serviceability of the structures. According to the observations, the modeled tunnels are vulnerable to reverse fault rupture and but the functionality loss is not abrupt, and the tunnel will be able to tolerate some fault displacements. By monitoring the progress of damage states by increasing PGD, the fragility curves corresponding to each damage state were plotted and interpreted in related figures.

关键词: reverse fault rupture     continuous tunnel     geotechnical centrifuge     ground surface deformations     fragility curves    

Experimental measurement of double-K fracture parameters of concrete with small-size aggregates

ZHANG Xiufang, XU Shilang, ZHENG Shuang

《结构与土木工程前沿(英文)》 2007年 第1卷 第4期   页码 448-457 doi: 10.1007/s11709-007-0061-8

摘要: The double- fracture model can well describe the development of cracks undergoing during the entire fracture process in concrete. Therefore, it has been selected as the theoretical basis of the Norm for fracture test of

关键词: development     concrete     theoretical     double- fracture    

Numerical study of thermal characteristics of double skin facade system with middle shade

Shaoning LIU, Xiangfei KONG, Hua YANG, Minchao FAN, Xin ZHAN

《能源前沿(英文)》 2021年 第15卷 第1期   页码 222-234 doi: 10.1007/s11708-017-0480-8

摘要: Architectural shade is an effective method for improving building energy efficiency. A new shade combined with the double skin façade (DSF) system, called middle shade (MS), was introduced and developed for buildings. In this paper, a 3D dynamic simulation was conducted to analyze the influence of MS combined with DSF on the indoor thermal characteristics. The research on MS for DSF involves the temperature, the ventilation rate, the velocity distribution of the air flow duct, and the indoor temperature. The results show that the angle and position of the shade in the three seasons are different, and different conditions effectively enhance the indoor thermal characteristics. In summer, the appearance of MS in DSF makes the indoor temperature significantly lower. The indoor temperature is obviously lower than that of the air flow duct, and the temperature of the air flow duct is less affected by MS. The influence of the position of blinds on indoor temperature and ventilation rate is greater than the influence of the angle of blinds. According to the climate characteristics of winter and transition season, in winter, early spring, and late autumn, the indoor temperature decreases with the increase of the position of blinds at daytime, but the opposite is true at night. The results found in this paper can provide reference for the design and use of MS combined with DSF in hot summer and cold winter zone.

关键词: middle shade     position     thermal characteristics     double skin facade    

Comparative study on foundation treatment methods of immersed tunnels in China

Shaochun WANG, Xuehui ZHANG, Yun BAI

《结构与土木工程前沿(英文)》 2020年 第14卷 第1期   页码 82-93 doi: 10.1007/s11709-019-0575-x

摘要: Based on engineering practices of four typical traffic immersed tunnels built in China, this paper details the features of the four dominant foundation treatment methods for immersed tunnel construction: pile foundation, sand flow foundation, grouting foundation, and gravel bedding foundation. Subsoil stress time-history of different method are specified first, plus a summary of settlement assessment method for foundation quality control. Further, a comprehensive comparison of settlement and cost of these four foundation treatment methods is conducted to highlights the specific merits, disadvantages and conditions encountered in each foundation treatment method, based on real projects information. The findings of this article could henceforth be applied to foundation treatment work in immersed tube tunnel construction.

关键词: foundation treatment method     immersed tunnel     subsoil stress     settlement    

Moment-curvature relationship of FRP-concrete-steel double-skin tubular members

Mingxue LIU, Jiaru QIAN

《结构与土木工程前沿(英文)》 2009年 第3卷 第1期   页码 25-31 doi: 10.1007/s11709-009-0012-7

摘要: Tests were conducted on 3 specimens to study the flexural behavior of fiber reinforced polymer (FRP)-concrete-steel double-skin tubular members (DSTMs). The strip method was used to calculate the section moment-curvature curves of the 3 specimens and 12 models. A theoretical formula is presented for the flexural strength of DSTMs. The test results show that the tension zone of the specimen FRP tubes was in hoop compression while the compression zone was in hoop tension. The load-carrying capacity did not decrease even when the mid-span deflection reached about 1/24 of the span length. The tests, simulation and theoretical analysis resulted in a simplified formula for the flexural strength of DSTMs and a tri-linear moment-curvature model was expressed as a function of the section bending stiffness for DSTMs.

关键词: fiber reinforced polymer (FRP)     concrete     steel     double-skin tubular members (DSTMs)     moment-curvature curve     flexural strength    

Connection of the prefabricated updeck of road tunnels by a short lap-spliced joint using ultra-high-performance

《结构与土木工程前沿(英文)》   页码 870-883 doi: 10.1007/s11709-023-0977-7

摘要: Prefabricated internal structures of road tunnels, consisting of precast elements and the connections between them, provide advantages in terms of quality control and manufacturing costs. However, the limited construction space in tunnels creates challenges for on-site assembly. To identify feasible connecting joints, flexural tests of precast straight beams connected by welding-spliced or lap-spliced reinforcements embedded in normal concrete or ultra-high-performance fiber-reinforced concrete (UHPFRC) are first performed and analyzed. With an improvement in the strength grade of the closure concrete for the lap-spliced joint, the failure of the beam transforms from a brittle splitting mode to a ductile flexural mode. The beam connected by UHPFRC100 with short lap-spliced reinforcements can achieve almost equivalent mechanical performance in terms of the bearing capacity, ductility, and stiffness as the beam connected by normal concrete with welding-spliced reinforcements. This favorable solution is then applied to the connection of neighboring updeck slabs resting on columns in a double-deck tunnel. The applicability is validated by flexural tests of T-shaped joints, which, fail in a ductile fashion dominated by the ultimate bearing capacity of the precast elements, similar to the corresponding straight beam. The utilization of UHPFRC significantly reduces the required lap-splice length of reinforcements owing to its strong bonding strength.

关键词: UHPFRC     prefabricated updeck     road tunnel     lap-spliced rebars     flexural tests    

Enhancement of distillate output of double basin solar still with vacuum tubes

Hitesh N PANCHAL, P K SHAH

《能源前沿(英文)》 2014年 第8卷 第1期   页码 101-109 doi: 10.1007/s11708-014-0299-5

摘要: The latent heat of condensation is lost to the atmosphere; hence it is not utilized to increase distillate output of single basin solar stills. This difficulty was overcome by attaching an additional basin to the main basin. The performance of the double basin solar still was also increased by attaching vacuum tubes to the lower basin; hence the lower basin possessed a higher temperature throughout the day. The latent heat of condensation of the bottom basin was also utilized to increase distillate. But the distillate output of the top basin was even lower compared with that of the bottom basin. This paper proposed a novel approach to increase the distillate output of the double basin solar still attached with vacuum tubes by introducing different sensible energy storage materials like pebbles, black granite gravel and calcium stones to increase the basin area. Experiments were conducted in climate conditions of Mehsana (23.6000° N, 72.4000° E) Gujarat from April to September 2013 with a constant water depth of 2 cm in the top basin with and without the use of basin materials. The results showed that the distillate output of basin material with calcium stones is greater (74%) compared with that of black granite gravel and pebbles. The integration of vacuum tubes with solar still greatly increases the distillate output of the solar still by providing hot water at the lower basin.

关键词: double basin solar still     calcium stones     pebbles     granite gravel     distillate output    

Latest development of double perovskite electrode materials for solid oxide fuel cells: a review

Shammya AFROZE, AfizulHakem KARIM, Quentin CHEOK, Sten ERIKSSON, Abul K. AZAD

《能源前沿(英文)》 2019年 第13卷 第4期   页码 770-797 doi: 10.1007/s11708-019-0651-x

摘要: Recently, the development and fabrication of electrode component of the solid oxide fuel cell (SOFC) have gained a significant importance, especially after the advent of electrode supported SOFCs. The function of the electrode involves the facilitation of fuel gas diffusion, oxidation of the fuel, transport of electrons, and transport of the byproduct of the electrochemical reaction. Impressive progress has been made in the development of alternative electrode materials with mixed conducting properties and a few of the other composite cermets. During the operation of a SOFC, it is necessary to avoid carburization and sulfidation problems. The present review focuses on the various aspects pertaining to a potential electrode material, the double perovskite, as an anode and cathode in the SOFC. More than 150 SOFCs electrode compositions which had been investigated in the literature have been analyzed. An evaluation has been performed in terms of phase, structure, diffraction pattern, electrical conductivity, and power density. Various methods adopted to determine the quality of electrode component have been provided in detail. This review comprises the literature values to suggest possible direction for future research.

关键词: double perovskites     electrode materials     hydrocarbon fuel     solid oxide fuel cells    

Nanosilver anchored alginate/poly(acrylic acid/acrylamide) double-network hydrogel composites for efficient

《化学科学与工程前沿(英文)》 2023年 第17卷 第7期   页码 893-905 doi: 10.1007/s11705-022-2290-8

摘要: A novel alginate/poly(acrylic acid/acrylamide) double-network hydrogel composite with silver nanoparticles was successfully fabricated using the sol–gel method. The presence of carboxyl and amide groups in the network structure provided abundant active sites for complexing silver ions, facilitating the in situ reduction and confinement of silver nanoparticles. In batch experiments, the optimal silver loading was 20%, and 5 mmol·L–1 of p-nitrophenol was completely degraded in 113 s with a rate constant value of 4.057 × 10−2 s–1. In the tap water system and simulated seawater system, the degradation time of p-nitrophenol at the same concentration was 261 and 276 s, respectively, with a conversion rate above 99%. In the fixed-bed experiment, the conversion rate remained above 74% after 3 h at a flowing rate of 7 mL·min–1. After 8 cycling tests, the conversion rate remained at 98.7%. Moreover, the catalyst exhibited outstanding performance in the degradation experiment of four typical organic dyes.

关键词: double-network hydrogel     dye degradation     silver nanoparticles     alginate    

标题 作者 时间 类型 操作

Structural design and mechanical responses of closely spaced super-span double tunnels in strongly weathered

Jiaxin HE; Shaohui HE; Xiabing LIU; Jinlei ZHENG

期刊论文

Weakening behavior of waterproof performance in joints of shield tunnels under adjacent constructions

期刊论文

铁路隧道建设理念和设计原则

王梦恕,张梅

期刊论文

Damage on lining concrete in highway tunnels under combined sulfate and chloride attack

Rongrong YIN, Chenchen ZHANG, Qing WU, Baocheng LI, He XIE

期刊论文

Efficient Identification of water conveyance tunnels siltation based on ensemble deep learning

Xinbin WU; Junjie LI; Linlin WANG

期刊论文

Influence of advanced engineering measures on displacement and stress field of surrounding rock in tunnels

期刊论文

Centrifuge experiments for shallow tunnels at active reverse fault intersection

Mehdi SABAGH, Abbas GHALANDARZADEH

期刊论文

Experimental measurement of double-K fracture parameters of concrete with small-size aggregates

ZHANG Xiufang, XU Shilang, ZHENG Shuang

期刊论文

Numerical study of thermal characteristics of double skin facade system with middle shade

Shaoning LIU, Xiangfei KONG, Hua YANG, Minchao FAN, Xin ZHAN

期刊论文

Comparative study on foundation treatment methods of immersed tunnels in China

Shaochun WANG, Xuehui ZHANG, Yun BAI

期刊论文

Moment-curvature relationship of FRP-concrete-steel double-skin tubular members

Mingxue LIU, Jiaru QIAN

期刊论文

Connection of the prefabricated updeck of road tunnels by a short lap-spliced joint using ultra-high-performance

期刊论文

Enhancement of distillate output of double basin solar still with vacuum tubes

Hitesh N PANCHAL, P K SHAH

期刊论文

Latest development of double perovskite electrode materials for solid oxide fuel cells: a review

Shammya AFROZE, AfizulHakem KARIM, Quentin CHEOK, Sten ERIKSSON, Abul K. AZAD

期刊论文

Nanosilver anchored alginate/poly(acrylic acid/acrylamide) double-network hydrogel composites for efficient

期刊论文